Narrated by and starring Sir Paul McCartney, PETA's shocking new video takes its inspiration from the most well-known quote in the animal rights movement and offers a brief glimpse behind the walls of slaughterhouses, factory farms, live-animal transport and the fishing industry.

By teaming up with PETA to produce the powerful video -- titled, "Glass Walls" -- Sir Paul is helping to uncover the horrific abuse that the meat and dairy industries inflicts on animals to provide consumers with cheap burgers, nuggets and other products. He also explains the massive cost to the environment for which the meat industry is directly responsible.

Billions of individual animals are violently killed for their flesh every year -- whilst others spend almost their entire lives confined to filthy, cramped conditions, where they are forced to produce seemingly endless supplies of eggs or gallons of milk.